The newly released footage shows researchers returning to the regions between November 2016 and March 2017 to find a potential fourth bleaching episode in the central reef, but Hughes did not believe it will be as catastrophic as previous year.

The temperature increase affecting the Great Barrier Reef is partially down a particularly strong El Nino climate cycle, on top of global warming. Even this year the reefs are expected to experience the bleaching phenomenon even though it won't be as severe as last year.

"Globally these [bleaching] events have become the new normal, and the time between them is getting shorter and shorter", Professor Terry Hughes, of James Cook University and the author of the study, told the Australian Broadcasting Corporation. The original living coral of the Great Barrier Reef is much more handsome than the dead pieces that are being left behind after these bleaching events occur.

By analysing individual reefs, the researchers discovered why some corals are more prone to bleaching than others.

A third massive bleaching battered the reef in 2016, according to a paper published Wednesday in Nature. It takes around 15 years for relatively fast-growing corals to recover from a significant disturbance like bleaching or a cyclone, Connolly explained.

Bleaching is primarily caused by prolonged exposure to high sea surface temperatures (SSTs).

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"Just a few months ago, these corals were full of colour and life". Hughes led the team that conducted aerial surveys to document the bleaching a year ago, as well as subsequent surveys to assess just how much of that bleaching turned into dying.

Dr Hughes is now doing aerial surveys of the reef following evidence of a 2017 bleaching event. One worrisome finding is that clean water, a necessity for a healthy reef system, is not enough for the living structure to fix itself after a bleaching event occurs due to elevated ocean temperatures.

INSKEEP: That's what Mia Hoogenboom saw while exploring the Great Barrier Reef. That was the third and worst sever bleaching.

Repeated damage to the Great Barrier Reef may also see UNESCO's World Heritage Committee reconsider its decision in 2015 not to put the Great Barrier Reef on its "in danger" list.

Significant chunks of the reef, dotted across hundreds of miles of the northern sector, were recently found bleached and dead - something previously estimated to be a full three-decades from becoming a reality.

Unseasonably warm waters threatens to cause bleaching of the central region of the Great Barrier Reef, which avoided the large-scale damage from the bleaching in 2016. "I think we've got a narrowing window of opportunity, to put it optimistically - or to put it pessimistically, we're running out of time".